Rolls-Royce has taken a significant step towards realising the ambition to provide hybrid-electric propulsion systems for the next generation of aviation.

With successful ground tests of a hybrid system using the M250 gas turbine – a highly successful engine usually powering helicopters.

The tests are part of one of the world’s most comprehensive hybrid aerospace turbine engine development and integration programmes and pave the way for experimental flights on aircraft in 2021.

Rolls-Royce successfully tested the hybrid version of the M250 gas turbine in a ground demonstration setting in three operating modes: Series Hybrid, Parallel Hybrid and Turbo-Electric.

The M250 hybrid is planned to be used as a propulsion plant with power ranging from 500kW to 1MW and has the potential to transform aviation power. The system will be used across a range of transport platforms to enable distributed electric propulsion, including EVTOLs (hybrid electric vertical take-off and landing vehicles), general aviation aircraft and hybrid helicopters.

Complete engine testing took place at the state-of-the-art facility in Indianapolis, US, where each component and sub-system of the hybrid engine was individually tested for electrical performance. These tests included simulating use across take-off, cruise, landing and taxiing and confirmed the system’s suitability for a range of transport platforms including aircraft with a range of up to 1000 miles and weighing up to 2000kg.

This would support the Rolls-Royce EVTOL concept which was unveiled during the Farnborough Air Show in the UK last year as well as meeting many other customers’ requirements.

The next step is to further advance the hybrid propulsion system towards integration on an aircraft and experimental flights in 2021. The M250 hybrid power pack complements the AE 2100 2.5MW system being developed for larger aircraft, including regional aviation, and is being tested with Airbus on the E-Fan X demonstrator platform.